Heretofore, contacts between microwave coaxial connectors generally have been made by pushing on a pushrod, spring-return connected to an electrically-conductive reed or switch blade which positions the reed in a position bridging across conductive center pins of the connector. Typically the conductive parts are constructed of gold-plated beryllium copper which provides very good solderability, wear and RF qualities. Switching of the positions of a mechanical switch actuator can take place both in the power-off and power-on conditions. The pushrods can be actuated individually by actuating coils above each pushrod or a rotary drive may be used to sequence through an angular travel to depress each of the array of pushrods one-by-one. Single-pole-double throw (SPDT) coaxial switches have been employed to alter the path of an incoming signal to one or the other of two outputs or to select one input for an output. Particularly, current T-switches for operating a 6-reed standard arrangement or array 10 of reeds shown in FIG. 1 utilize a series of dielectric pushrods 11, each attached to a series of reeds 12a and 12b. Depression of one pushrod moves the reed 12a to electrically bridge across RF conductor contacts 14 and 15 and depression of another pushrod moves reed 12b to bridge across contacts 14 and 16, when the reeds are depressed by a force vector against a particular pushrod 11. FIG. 1 shows short reed 12a and long reed 12b in a switch open condition, while reed 12c and 12d are in a switch closed condition between contacts 14 and 17 and 15 and 16, respectively. Return springs 18 return the pushrods and reeds to their normal "unpushed" position upon release of the force vector. In the open stroke the reed is forced against the top of the cavity (FIG. 3). This effectively presents a waveguide below cut off frequency.
FIGS. 2 and 3 illustrate a one-directional rotary drive 20 having coils 21 with cores 19 which are indexed to a desired pushrod 18 and move about shaft 22.
The reed actuator is based on interaction between two layers of magnets. One layer 23 consists of six magnets attached to dielectric pushrods 18 placed in the middle of each reed. All magnets are magnetized parallel to the direction of reed movement and have the same polarity.
The second layer 24 comprises another set of six magnets contained in the lower portion of a rotating disk or armature 29. The axis of magnetization for these magnets is the same as for the magnets in the first layer. However, four of these magnets are placed to attract the magnets from the first layer, and two of the magnets, 180.degree. apart, are of opposite polarity. These two magnets repel and force a pair of reeds to make contact. At the same time, the rest of the reeds (not shown in the Fig.) are grounded to the top of the RF body as a result of attraction between the magnets.
The rotating disk has six stable positions as a result of the magnets' interaction with cores which latch the disk every 60.degree.. During a full turn of the disk, each position of the switch is chosen twice. As shown in FIGS. 4A-4F, six positions of the disk actually represent three unique RF contact arrangements. Generally, the reed actuator assures proper reed arrangement for all three positions of the switch and latches the reeds in each position.
The rotating actuator or armature is based on electromagnetic interaction between a layer of six magnets 24a and six drive coils. This layer of magnets is contained in the upper rotating disk and has the same axis of magnetization as other magnets in the reed actuator discussed previously. However, those upper magnets are polarized alternatively so that every other magnet has the same polarity. There is a magnetic shielding plate 24c in the middle of the rotating actuator to isolate the magnetic forces from the upper and lower layers of magnets. To be able to change the position of the switch, it is necessary to rotate the disk. To accomplish this function, a multicoil drive approach has been used.
The drive consists of six coils 21 which are wound directly on ferromagnetic cores 19 and attached to a common ferromagnetic magnet plate 27. The coils are equally spaced on the same diameter as the magnets in the rotating disk 23, but the whole coil assembly is offset about 15.degree. from the position of the magnets. To obtain all three positions, shown in FIGS. 4A-4F, it is necessary to energize the coils with three separate voltage pulses. Each pulse shall have an opposite voltage polarity from the preceding pulse. The drive mechanism will latch the 3-switching positions sequentially and is unable to select any one of three switching positions randomly.
As can be envisioned, if one desires to rotate from the approximately one o'clock position (FIG. 2) to the seven o'clock position, one must first pass by two intervening positions. This takes extra time, travel distance and extra energy which may be a premium, particularly in, for example, a space application. On the top of magnet plate 27 there is placed a printed circuit board (PCB) with electronic control elements (not shown) and is shown removed in FIG. 3. FIG. 4 illustrates six positions A-F of this prior art rotary drive, particularly showing the six types of connections made possibly by six reeds between the various contacts 14, 15, 16 and 17.